使用一個核心數據屬性填充數組

Question

我在將條目從一個屬性放入數組中時遇到了一些問題。這個數組然後將被用在UIPickerview中。語言是Swift。

在swift和Core Data中有許多關於Pickerviews的快速教程。但我還沒有找到解釋如何用一個屬性填充數組的方法。

更糟糕的是，我仍然很難將目標c轉換成swift。

所以我有兩個問題：

1我是正確的解決方案，從一個屬性建立一個數組，然後用這個數組內容填寫Pickerview？

2你如何在swift中獲得該數組？

objective c code on core data => array

---

從鏈接

目標C：

NSManagedObjectContext *managedObjectContext = [self managedObjectContext]; 
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] 
           initWithEntityName:@"WeightLog"]; 
self.contactarray = [[managedObjectContext executeFetchRequest:fetchRequest 
                 error:nil] mutableCopy]; 

titleNames = [[NSMutableArray alloc] init]; 
for (int i =0; i<=self.contactarray.count; i++) { 
    NSManagedObject *device = [self.contactarray objectAtIndex:i]; 
    [titleNames addObject:device]; 
} 

---

我不能在斯威夫特寫的部分：

NSManagedObjectContext *managedObjectContext = [self managedObjectContext]; 
     NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] 
      initWithEntityName:@"WeightLog"]; 
     self.contactarray = [[managedObjectContext executeFetchRequest:fetchRequest 
     error:nil] mutableCopy]; 

謝謝！

---

編輯： 工作代碼！

var myTitle: String = "" 


var appDel:AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate) 
     var context:NSManagedObjectContext = appDel.managedObjectContext! 

     let fetchRequest = NSFetchRequest(entityName:"MyEntity") 
     var myTitles: [String] = [] 
     if let myLogs = context.executeFetchRequest(fetchRequest, error: nil) { 
      myTitles = myLogs.map { $0.myTitle } // get an array of the 'myTitle' attributes 
      println(myTitles) 

Answer 1

我只是在這裏打字，所以不知道如果它甚至編譯：

let moc = self.managedObjectContext() 
let fetchRequest = NSFetchRequest(entityName:"WeightLog") 
var titleNames: [String] = [] 
if let weightLogs = moc.executeFetchRequest(fetchRequest, error: nil) as? [WeightLog] { 
    titleNames = weightLogs.map { $0.title } // get an array of the 'title' attributes 
} 

如果你從方法返回的titleNames數組，那麼我會寫這樣的，即不使用var titleNames：

let moc = self.managedObjectContext() 
let fetchRequest = NSFetchRequest(entityName:"WeightLog") 
if let weightLogs = moc.executeFetchRequest(fetchRequest, error: nil) as? [WeightLog] { 
    return weightLogs.map { $0.title } // get an array of the 'title' attributes 
} else { 
    return [] 
} 

Answer 2

lazy var managedObjectContext : NSManagedObjectContext? = { 
    let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate 

    if let managedObjectContext = appDelegate.managedObjectContext 
    { 
     return managedObjectContext 
    } 
    else 
    { 
     return nil 
    } 
}() 

let fetchRequest = NSFetchRequest(entityName: "Entity") 

if let fetchResults = managedObjectContext!.executeFetchRequest(fetchRequest, error: nil) as? [Entity] 
{ 

    for info in fetchResults 
    { 
     println(info.valueForKey("keyname")); 
    } 
}